@Zeno. several solutions to a cone-shaped bowl with a high draft . meerschaum chips, pumice crumbs or volcanic clay, crushed terra cotta shards,
I have even heard of rice grains being used. There are also tiny screen baskets available online for just that application: I've seen them on either SP or TP.
A more permanent solution is to mix some pipe mud and literally fill the floor of the bowl to a comfortable draw. I've used this method for several cobs to eliminate the "junk bucket" beneath the shank insert. I use fine fireplace ash, with a 50% water/sodium silicate solution. Some people raise concerns about sodium silicate but it is a common glazing solution in pottery and used for everything from garden gnomes to dinnerware. Research pipe mud well before you apply it for a good pipe. I taught myself on used up cobs. I cure the stummel in the oven at minimum heat for 2-4 hours depending on the size of the bowl and the depth of the patch. It also works well for charring pits.
I have even heard of rice grains being used. There are also tiny screen baskets available online for just that application: I've seen them on either SP or TP.
A more permanent solution is to mix some pipe mud and literally fill the floor of the bowl to a comfortable draw. I've used this method for several cobs to eliminate the "junk bucket" beneath the shank insert. I use fine fireplace ash, with a 50% water/sodium silicate solution. Some people raise concerns about sodium silicate but it is a common glazing solution in pottery and used for everything from garden gnomes to dinnerware. Research pipe mud well before you apply it for a good pipe. I taught myself on used up cobs. I cure the stummel in the oven at minimum heat for 2-4 hours depending on the size of the bowl and the depth of the patch. It also works well for charring pits.